Stachybotrys microspora triprenyl phenol (SMTP) compounds are a group of compounds that are produced by filamentous fungi and have a triprenyl phenol skeleton, and known to have a thrombolysis enhancing activity and an angiogenesis inhibiting activity (for example, see Japanese Patent Application Laid-Open (JP-A) No. 2004-224737, Japanese Patent No. 4313049, and International Publication No. WO 2007/111203). With regard to the thrombolysis enhancing activity, a mechanism of action has been suggested in which SMTP compounds induce a conformational change in plasminogen, and resultantly increase susceptibility of plasminogen to t-PA and enhance the binding of plasminogen to thrombi, thereby enhancing thrombolysis (for example, see FEBS Letter 1997; 418: 58-62). SMTP compounds are expected to serve as a therapeutic agent for thrombotic stroke (for example, see N. -S. Arch. Pharmacol., 382, 245-253 (2010)), a cytoprotective agent (for example, see International Publication No. WO 2011/004620), or the like.
The SMTP compounds have a geranylmethyl moiety, a tricyclic y-lactam moiety containing a γ-lactam ring, and a side chain moiety linked to the nitrogen atom of the lactam ring. It is suggested that the activity as a plasminogen modulator depends on the structure of the side chain moiety linked to the nitrogen atom of the lactam ring, from among the moieties described above (for example, see J. Antibiot., 63, 589-593(2010)).